Three Competing Open Letters in Five Days: 235 Companies Back Open Weights, Anthropic Refuses to Sign, Then 1,324 Lab Employees Ask Washington to Build a Brake
Simon Willison's August 2 roundup lays out three July letters that split the industry: 'Open Weights and American AI Leadership' (July 24, Microsoft-shepherded, now 235 signatory companies including NVIDIA, Amazon, Y Combinator, the Linux Foundation and — after initially abstaining — OpenAI); Anthropic's separate July 27 rebuttal from Dario Amodei; and 'Pacing the Frontier' (July 28), which Amodei and Jack Clark did sign. The open-weights letter grew from ~25 signatories at launch to 50 within a day to 235 by August 2, and explicitly endorses distillation as 'a widely used technique for model improvement' — the exact practice Amodei's response wants cracked down on at 'industrial scale.' For builders the practical read is that no US ban on open-weight models is coming, but a compute-threshold safety-testing regime that applies to open and closed models alike now has backing from the one lab that stayed off the coalition letter.
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